The Yuan Lab at East China Normal University reported a method to enhance the stability of TaS2 photodetectors through Co intercalation. The related findings were published online in ACS Materials Letters under the title "Enhanced Stability of TaS2 Photodetector by Co Intercalation."
Due to the large specific surface area of two-dimensional materials, two-dimensional devices are often sensitive to environmental factors, posing challenges to their reliability and stability. Enhancing the stability of these devices involves addressing issues related to chemical stability, structural stability, and thermal stability. Current strategies to mitigate these problems include surface protection techniques, such as covering with stable hexagonal boron nitride using transfer techniques or coating with metal oxide layers via atomic layer deposition, which can prevent chemical reactions between the materials and the surrounding atmosphere. Surface treatments can also improve stability by altering the surface chemical properties of the two-dimensional materials. However, these approaches require additional external manipulation of the materials. This study introduces intercalation technology as a potential way to enhance the stability of two-dimensional materials.
In this work, we compared the photoelectric response of micro-nano devices made from 2H-TaS2 and Co0.22TaS2 crystals with Co intercalation. Our results indicate that Co intercalation significantly enhances the stability and performance of the photodetectors. We measured an effective response time of 182 μs for the intercalated devices using frequency modulation measurements; the photoelectric response mainly originates from the photothermal electric mechanism, as determined by bias-resolved photocurrent and spatially scanned photocurrent distribution maps. The intrinsic devices exhibited a noticeable degradation in responsivity after a few hours of illumination, while the Co intercalated devices maintained nearly constant performance, with negligible performance degradation. After two months, the optical responsivity remained at 98.8%, corresponding to an estimated operational lifespan of about 9.4 years. Additionally, Co intercalation also improved device performance, achieving approximately a twofold increase in responsivity. Control experiments conducted under vacuum conditions ruled out the effects of surface molecular adsorption. Through DFT calculations, we propose that this enhanced stability may arise from intercalated atoms effectively blocking water and oxygen molecules from entering the van der Waals gaps. This suppression reduces the potential for interlayer oxidation and photochemical reactions, thereby significantly enhancing the material's resistance to degradation and stability. These results provide an effective method for improving the stability and durability of two-dimensional optoelectronic devices.
This project was completed by the Yuan Xiang research team at East China Normal University. The work was supported and funded by the National Natural Science Foundation, the The Science and Technology Commission of Shanghai Municipality, and East China Normal University. The paper lists East China Normal University as the first affiliation, with Yuan Xiang as the corresponding author, and master's student Liu Binglin and doctoral student Meng Xianghao from East China Normal University as co-first authors.
More information: https://pubs.acs.org/doi/10.1021/acsmaterialslett.4c01919
